In a scroll compressor, a stationary scroll and an orbiting scroll are meshed to form a plurality of closed spaces. The volume of the formed closed space decreases gradually from the outer edge toward the central part. As shown in FIGS. 1 and 2, an orbiting scroll 10 is led to orbit a stationary scroll 11 such that low-pressure working fluid a is sucked in via a suction port b, compressed through continuous orbital motion of the orbiting scroll 10, and discharged at high-pressure state via a discharge port c at the center of the stationary scroll 11. The compression stroke of working fluid is thus completed.
As shown in FIG. 3, a scroll compressor in prior art comprises an orbiting scroll 10, a stationary scroll 11, an isolating block 12, an Oldham ring 13, a frame 14, an eccentric shaft 15, a motor rotor 16, and a motor stator 17. The eccentric shaft 15 is tightly matched with the motor rotor 16. An axially passive ring 18 is installed at the top end of the eccentric shaft 15. When the motor is turned on, the eccentric shaft 15 is led to rotate by the motor rotor 16, and the orbiting scroll 10 is led to orbit eccentrically the center of the motor rotor 16 by the ring 18 at the top of the eccentric shaft 15. The Oldham ring 13 is installed at the top of the frame 14. When the orbiting scroll 10 is driven, the Oldham 13 can be used to control the orbiting scroll such that it can orbit but can not rotate on its axis. The orbiting scroll 10 is pressed by the stationary scroll 11 to stick to the frame 14. The stationary scroll 11 is fixed on the frame 14 via a passive blocking plate 19. The passive blocking plate 19 allows the stationary scroll 11 to make a little axial motion. The orbiting scroll 10 and the stationary scroll 11 respectively have a plurality of spiral scroll plates 20 and 21 with a plurality of compression rooms formed between them. The isolating block 12 is fixed in a shell 22 of the scroll compressor and partitions the shell 22 into a high-pressure chamber and a low-pressure chamber. A through hole 24 is disposed at the center of the isolating block 12 to connect the two chambers. When low-pressure working fluid is sucked into the compression rooms via a suction port b, the working fluid is pressed to be discharged via a through discharge port c at the center of the stationary scroll 11 through the continuous orbital motion of the orbiting scroll 10. High-pressure working fluid is then discharged out of the scroll compressor via an exit 23 at the shell 22 of the scroll compressor. However, in the above mentioned scroll compressor of prior art, another axially passive ring 18 needs to be lagged connectedly to the eccentric shaft 15. Gap between the ring and the eccentric shaft will be large because of the axially passive function, resulting in louder noise.
Another scroll compressor of prior art has no axially passive rings. But the eccentric shaft (not shown) is integrally formed such that consumed material is more. Molding and forging methods are needed for manufacture such that production cost is higher. Moreover, the eccentric shaft must be assembled in advance with the frame. Flexibility of assembly process is thus small.